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Thread: 40 Meter coil length for Butternut HF6V

  1. #1

    Default 40 Meter coil length for Butternut HF6V

    I'm starting to rebuild my Butternut HF6V and have to build another coil for 40 meters since mine was stretched out and ripped apart. I can probably find replacement aluminum wire to rebuild the coil but I have no idea what the total physical length of the coil is. Does anyone know what the length of the 40meter coil is, or at least maybe the number of turns of one you already have and the diameter of the coil?

    Thanks for any information on this subject.

    Ralph in Sacramento

  2. #2


    I found this picture on google. It looks like 10 turns.

    Length, diameter and number of turns all play a role in determining a coils inductance. A coil is used to introduce inductive reactance to an antenna that exhibits capacitive reactance (usually from the antenna being electrically shorter than any given odd multiple of quarter wavelengths) such that they cancel out leaving just a resistive component - while at the same time both are made such that the remaining purely resistive portion of the impedance matches the feed line. I would go with a bit more coil as you think is needed so you have room to remove some in the tuning process.

    Attachment 1073

  3. #3
    K7KBN's Avatar
    Join Date
    Jul 2008
    Bremerton WA USA


    You might want to replace aluminum wire with equal size copper or tinned copper. If you have to solder any connections, you'll be really unhappy with aluminum. And as Bandon said, make it a bit longer than you think it should be.
    Pat K7KBN
    Semper ubi sub ubi.

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